A passenger conveyor, such as an escalator and a moving walkway, includes a plurality of steps each provided with step rollers on the front and rear sides thereof. These steps are linked to one another in an endless manner with a step chain. The driving of the step chain causes all the steps to move to circulate between an entrance and an exit in a synchronized manner with no space between each adjacent two steps. In the case of an escalator, each step is guided with the rollers supported on step guide rails installed in a truss while traveling on the forward path side. Accordingly, while a footboard of each step is held horizontal, the step travels in a horizontal direction in a vicinity of the entrance and in a vicinity of the exit, and also travels in an ascending or descending direction inclined at approximately 30° in the intermediate portion extending from the vicinity of the entrance to the vicinity of the exit. The rollers of each step are guided by reverse rails at a returning section in an upstairs section or a downstairs section, so that the traveling direction and the attitude of each step are reversed. On the return path side, each step travels in a state where the rollers of the step are guided by other step guide rails, which are provided downward of the step guide rails on the forward path side in the truss.
As the driving device for driving the step chain linking the steps to one another, often employed is a device which is provided in a machine room in a vicinity of the entrance or the exit on the upstairs side, and which is driven with a sprocket provided in the returning end section of the step chain.
There also is another type of device which is provided in the intermediate portion of the truss, and which is driven with a rack or the like engaged with the step chain. For the driving device installed in the intermediate portion of the truss, a roller reaction force at the returning section of the step chain is constant regardless of the floor height. Accordingly, the driving device of this type is advantageous in that components having certain strength can be used regardless of the floor height.
In the case of an escalator having a high floor height, it has also been proposed to use, in combination, a driving device in which a returning end section of the step chain is driven by a sprocket, and a driving device installed in the intermediate portion of the truss. This is for the following reason. When a floor height is high, a heavy load is imposed on the step chain. Accordingly, with the driving device at the returning end section of the step chain alone, the driving force is sometimes transmitted only insufficiently. In addition, not only in the case of the escalator having a high floor height, but also in the case of a moving walkway having a long traveling distance, with the driving device at the returning end section of the step chain alone, the driving force is sometimes transmitted only insufficiently. For this reason, it has been proposed to distribute, driving devices, each of which can provide a driving force in the middle of a long step chain (a portion other than the end sections where the step chain changes the direction so as to return). This makes it possible to move the long step chain and the series of steps connected to the step chain even in the above-described cases.
Such a passenger conveyor in which a driving device is provided in an intermediate portion of a truss has been disclosed, for example, in Patent Document 1 and Patent Document 2. In Patent Document 1, a drive pinion of a driving device installed in an intermediate portion is engaged with racks formed in link plate portions of a step chain, so that a driving force is transmitted from the driving device to the step chain. In Patent Document 2, a driving force is transmitted from a driving device installed in an intermediate portion of a truss by using a standard step chain instead of a special chain such as a chain with teeth. For achieving this, in the driving device, a rocking unit is attached to a rotary driving device with an eccentric shaft in between while rolling gear teeth, each having a trochoidal shape, are provided to the rocking unit. The rolling gear teeth are engaged with the step chain while the rocking unit performs a rocking movement due to the transmission of the rotational movement of the rotary driving device, so that a driving force is given to the step chain.
Descriptions will be given of the above-described passenger conveyor of the related art, in which a driving device is installed in the intermediate portion, and concurrently in which another driving device is also installed in a machine room in an end portion on the upstairs side. This passenger conveyor includes a plurality of steps each including a footboard on which a passenger stands, a stair riser connected to an end portion of the footboard, front-wheel rollers, and rear-wheel rollers. The front-wheel and rear-wheel rollers are provided to a frame to which the footboard and the stair riser are attached. The front-wheel rollers of each step are connected to an endless step chain at certain pitches. The step chain is looped around a driving wheel provided on the upstairs side and a coupled driving wheel provided on the downstairs side. A driving force is transmitted to the driving wheel from a driving device, so that the step chain moves to circulate between the driving wheel and the coupled driving wheel. Moreover, an intermediate driving device including a motor is installed in an intermediate inclined portion of the passenger conveyor, and is engaged with the step chain to transmit a driving force to the step chain. As the intermediate driving device, the passenger conveyor includes an intermediate driving device which gives a driving force to the step chain by the rocking movement of a rocking unit including rolling gear teeth, as described in Patent Document 2.
In accordance with the circulating movement of the step chain, the steps move to circulate. At this time, the front-wheel rollers are guided by forward-path-side front-wheel guide rails and also by return-path-side front-wheel guide rails, while the rear-wheel rollers are guided by front-path-side rear-wheel guide rails and also by return-path-side rear-wheel guide rails.
The intermediate driving device is arranged between the steps traveling on the forward path and the steps traveling on the return path. In particular, the motor, a reduction mechanism for transmitting the power of the motor and the like are housed in a space sandwiched between the lower end portions of the stair risers of the steps on the forward path side and the lower end portions of the stair risers of the steps on the return path side.
Patent Document 1: Japanese Patent Application Laid-open Publication No. Sho 61-166492
Patent Document 2: Japanese Patent Application Laid-open Publication No. 2002-128441